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 ;

 ; jcqntmmx.asm - sample data conversion and quantization (MMX)

 ;

 ; Copyright 2009 Pierre Ossman <ossman@cendio.se> for Cendio AB

 ;

 ; Based on

 ; x86 SIMD extension for IJG JPEG library

 ; Copyright (C) 1999-2006, MIYASAKA Masaru.

 ; For conditions of distribution and use, see copyright notice in jsimdext.inc

 ;

 ; This file should be assembled with NASM (Netwide Assembler),

 ; can *not* be assembled with Microsoft's MASM or any compatible

 ; assembler (including Borland's Turbo Assembler).

 ; NASM is available from http://nasm.sourceforge.net/ or

 ; http://sourceforge.net/project/showfiles.php?group_id=6208

 ;

 ; [TAB8]

 %include "jsimdext.inc"

 %include "jdct.inc"

 ; --------------------------------------------------------------------------

 	SECTION	SEG_TEXT

 	BITS	32

 ;

 ; Load data into workspace, applying unsigned->signed conversion

 ;

 ; GLOBAL(void)

 ; jsimd_convsamp_mmx (JSAMPARRAY sample_data, JDIMENSION start_col,

 ;                     DCTELEM * workspace);

 ;

 %define sample_data	ebp+8		; JSAMPARRAY sample_data

 %define start_col	ebp+12		; JDIMENSION start_col

 %define workspace	ebp+16		; DCTELEM * workspace

 	align	16

 	global	EXTN(jsimd_convsamp_mmx)

 EXTN(jsimd_convsamp_mmx):

 	push	ebp

 	mov	ebp,esp

 	push	ebx

 ;	push	ecx		; need not be preserved

 ;	push	edx		; need not be preserved

 	push	esi

 	push	edi

 	pxor	mm6,mm6			; mm6=(all 0's)

 	pcmpeqw	mm7,mm7

 	psllw	mm7,7			; mm7={0xFF80 0xFF80 0xFF80 0xFF80}

 	mov	esi, JSAMPARRAY [sample_data]	; (JSAMPROW *)

 	mov	eax, JDIMENSION [start_col]

 	mov	edi, POINTER [workspace]	; (DCTELEM *)

 	mov	ecx, DCTSIZE/4

 	alignx	16,7

 .convloop:

 	mov	ebx, JSAMPROW [esi+0*SIZEOF_JSAMPROW]	; (JSAMPLE *)

 	mov	edx, JSAMPROW [esi+1*SIZEOF_JSAMPROW]	; (JSAMPLE *)

 	movq	mm0, MMWORD [ebx+eax*SIZEOF_JSAMPLE]	; mm0=(01234567)

 	movq	mm1, MMWORD [edx+eax*SIZEOF_JSAMPLE]	; mm1=(89ABCDEF)

 	mov	ebx, JSAMPROW [esi+2*SIZEOF_JSAMPROW]	; (JSAMPLE *)

 	mov	edx, JSAMPROW [esi+3*SIZEOF_JSAMPROW]	; (JSAMPLE *)

 	movq	mm2, MMWORD [ebx+eax*SIZEOF_JSAMPLE]	; mm2=(GHIJKLMN)

 	movq	mm3, MMWORD [edx+eax*SIZEOF_JSAMPLE]	; mm3=(OPQRSTUV)

 	movq      mm4,mm0

 	punpcklbw mm0,mm6		; mm0=(0123)

 	punpckhbw mm4,mm6		; mm4=(4567)

 	movq      mm5,mm1

 	punpcklbw mm1,mm6		; mm1=(89AB)

 	punpckhbw mm5,mm6		; mm5=(CDEF)

 	paddw	mm0,mm7

 	paddw	mm4,mm7

 	paddw	mm1,mm7

 	paddw	mm5,mm7

 	movq	MMWORD [MMBLOCK(0,0,edi,SIZEOF_DCTELEM)], mm0

 	movq	MMWORD [MMBLOCK(0,1,edi,SIZEOF_DCTELEM)], mm4

 	movq	MMWORD [MMBLOCK(1,0,edi,SIZEOF_DCTELEM)], mm1

 	movq	MMWORD [MMBLOCK(1,1,edi,SIZEOF_DCTELEM)], mm5

 	movq      mm0,mm2

 	punpcklbw mm2,mm6		; mm2=(GHIJ)

 	punpckhbw mm0,mm6		; mm0=(KLMN)

 	movq      mm4,mm3

 	punpcklbw mm3,mm6		; mm3=(OPQR)

 	punpckhbw mm4,mm6		; mm4=(STUV)

 	paddw	mm2,mm7

 	paddw	mm0,mm7

 	paddw	mm3,mm7

 	paddw	mm4,mm7

 	movq	MMWORD [MMBLOCK(2,0,edi,SIZEOF_DCTELEM)], mm2

 	movq	MMWORD [MMBLOCK(2,1,edi,SIZEOF_DCTELEM)], mm0

 	movq	MMWORD [MMBLOCK(3,0,edi,SIZEOF_DCTELEM)], mm3

 	movq	MMWORD [MMBLOCK(3,1,edi,SIZEOF_DCTELEM)], mm4

 	add	esi, byte 4*SIZEOF_JSAMPROW

 	add	edi, byte 4*DCTSIZE*SIZEOF_DCTELEM

 	dec	ecx

 	jnz	short .convloop

 	emms		; empty MMX state

 	pop	edi

 	pop	esi

 ;	pop	edx		; need not be preserved

 ;	pop	ecx		; need not be preserved

 	pop	ebx

 	pop	ebp

 	ret

 ; --------------------------------------------------------------------------

 ;

 ; Quantize/descale the coefficients, and store into coef_block

 ;

 ; This implementation is based on an algorithm described in

 ;   "How to optimize for the Pentium family of microprocessors"

 ;   (http://www.agner.org/assem/).

 ;

 ; GLOBAL(void)

 ; jsimd_quantize_mmx (JCOEFPTR coef_block, DCTELEM * divisors,

 ;                     DCTELEM * workspace);

 ;

 %define RECIPROCAL(m,n,b) MMBLOCK(DCTSIZE*0+(m),(n),(b),SIZEOF_DCTELEM)

 %define CORRECTION(m,n,b) MMBLOCK(DCTSIZE*1+(m),(n),(b),SIZEOF_DCTELEM)

 %define SCALE(m,n,b)      MMBLOCK(DCTSIZE*2+(m),(n),(b),SIZEOF_DCTELEM)

 %define SHIFT(m,n,b)      MMBLOCK(DCTSIZE*3+(m),(n),(b),SIZEOF_DCTELEM)

 %define coef_block	ebp+8		; JCOEFPTR coef_block

 %define divisors	ebp+12		; DCTELEM * divisors

 %define workspace	ebp+16		; DCTELEM * workspace

 	align	16

 	global	EXTN(jsimd_quantize_mmx)

 EXTN(jsimd_quantize_mmx):

 	push	ebp

 	mov	ebp,esp

 ;	push	ebx		; unused

 ;	push	ecx		; unused

 ;	push	edx		; need not be preserved

 	push	esi

 	push	edi

 	mov	esi, POINTER [workspace]

 	mov	edx, POINTER [divisors]

 	mov	edi, JCOEFPTR [coef_block]

 	mov	ah, 2

 	alignx	16,7

 .quantloop1:

 	mov	al, DCTSIZE2/8/2

 	alignx	16,7

 .quantloop2:

 	movq	mm2, MMWORD [MMBLOCK(0,0,esi,SIZEOF_DCTELEM)]

 	movq	mm3, MMWORD [MMBLOCK(0,1,esi,SIZEOF_DCTELEM)]

 	movq	mm0,mm2

 	movq	mm1,mm3

 	psraw	mm2,(WORD_BIT-1)  ; -1 if value < 0, 0 otherwise

 	psraw	mm3,(WORD_BIT-1)

 	pxor	mm0,mm2   ; val = -val

 	pxor	mm1,mm3

 	psubw	mm0,mm2

 	psubw	mm1,mm3

 	;

 	; MMX is an annoyingly crappy instruction set. It has two

 	; misfeatures that are causing problems here:

 	;

 	; - All multiplications are signed.

 	;

 	; - The second operand for the shifts is not treated as packed.

 	;

 	;

 	; We work around the first problem by implementing this algorithm:

 	;

 	; unsigned long unsigned_multiply(unsigned short x, unsigned short y)

 	; {

 	;   enum { SHORT_BIT = 16 };

 	;   signed short sx = (signed short) x;

 	;   signed short sy = (signed short) y;

 	;   signed long sz;

 	; 

 	;   sz = (long) sx * (long) sy;     /* signed multiply */

 	; 

 	;   if (sx < 0) sz += (long) sy << SHORT_BIT;

 	;   if (sy < 0) sz += (long) sx << SHORT_BIT;

 	; 

 	;   return (unsigned long) sz;

 	; }

 	;

 	; (note that a negative sx adds _sy_ and vice versa)

 	;

 	; For the second problem, we replace the shift by a multiplication.

 	; Unfortunately that means we have to deal with the signed issue again.

 	;

 	paddw	mm0, MMWORD [CORRECTION(0,0,edx)]   ; correction + roundfactor

 	paddw	mm1, MMWORD [CORRECTION(0,1,edx)]

 	movq	mm4,mm0   ; store current value for later

 	movq	mm5,mm1

 	pmulhw	mm0, MMWORD [RECIPROCAL(0,0,edx)]   ; reciprocal

 	pmulhw	mm1, MMWORD [RECIPROCAL(0,1,edx)]

 	paddw	mm0,mm4		; reciprocal is always negative (MSB=1),

 	paddw	mm1,mm5   ; so we always need to add the initial value

 	                ; (input value is never negative as we

 	                ; inverted it at the start of this routine)

 	; here it gets a bit tricky as both scale

 	; and mm0/mm1 can be negative

 	movq	mm6, MMWORD [SCALE(0,0,edx)]	; scale

 	movq	mm7, MMWORD [SCALE(0,1,edx)]

 	movq	mm4,mm0

 	movq	mm5,mm1

 	pmulhw	mm0,mm6

 	pmulhw	mm1,mm7

 	psraw	mm6,(WORD_BIT-1)    ; determine if scale is negative

 	psraw	mm7,(WORD_BIT-1)

 	pand	mm6,mm4             ; and add input if it is

 	pand	mm7,mm5

 	paddw	mm0,mm6

 	paddw	mm1,mm7

 	psraw	mm4,(WORD_BIT-1)    ; then check if negative input 

 	psraw	mm5,(WORD_BIT-1)

 	pand	mm4, MMWORD [SCALE(0,0,edx)]	; and add scale if it is

 	pand	mm5, MMWORD [SCALE(0,1,edx)]

 	paddw	mm0,mm4

 	paddw	mm1,mm5

 	pxor	mm0,mm2   ; val = -val

 	pxor	mm1,mm3

 	psubw	mm0,mm2

 	psubw	mm1,mm3

 	movq	MMWORD [MMBLOCK(0,0,edi,SIZEOF_DCTELEM)], mm0

 	movq	MMWORD [MMBLOCK(0,1,edi,SIZEOF_DCTELEM)], mm1

 	add	esi, byte 8*SIZEOF_DCTELEM

 	add	edx, byte 8*SIZEOF_DCTELEM

 	add	edi, byte 8*SIZEOF_JCOEF

 	dec	al

 	jnz	near .quantloop2

 	dec	ah

 	jnz	near .quantloop1	; to avoid branch misprediction

 	emms		; empty MMX state

 	pop	edi

 	pop	esi

 ;	pop	edx		; need not be preserved

 ;	pop	ecx		; unused

 ;	pop	ebx		; unused

 	pop	ebp

 	ret

 ; For some reason, the OS X linker does not honor the request to align the

 ; segment unless we do this.

 	align	16